I think that it works fine for some people, but if your goal is lifting maximal weight, at some point, wearing a belt is going to necessary for most people. Wearing a belt doesn't eliminate the need for the trunk musculature to work hard under heavy weights, and core work can be done out side of squatting etc.

Ditto on the belts. C&Js, squats, jerks over 80ish percent. Some people never wear one at all. The heaviest C&J of all time was done without a belt, 266 kilos by Leonid Taranenko. Interestingly, he had done 265.5 a year earlier and he was wearing a belt then. I guess he just used it when he felt like he needed it. But I think most people who are pushing for top OL results wear a belt in C&J. You rarely see it in the snatch, but there are a couple of elite lifters who use it. Podobedova, 75 kilo world record holder in the women's division, wears a belt in the SN.